High-Precision Robust Broadband Ultrasonic Location and Orientation Estimation

This paper presents an indoor broadband ultrasonic system for estimation of a mobile device's 3-D location and three-axis orientation using beacons. It presents the first implementation and characterization of a real frequency hopping spread spectrum-based ultrasonic positioning system, a novel application of uniform circular array angle of arrival estimation techniques to indoor location-orientation estimation and a novel hybrid algorithm for location-orientation estimation. The performance of the system was assessed experimentally. The system has been shown to provide better accuracy, robustness to noise and multipath than other previously reported indoor ultrasonic location or orientation estimation systems with comparable range in the typical office environment tested. The prototype provided location estimates with an error of less than 1.5 cm and and error of less than 4.5deg in the yaw, 3deg in the pitch and 3.5deg in the roll, in 95% of cases.